What Size Ball Can Fit the Thule Replacement Bike Adapter ezHitch Cup

Updated 10/07/2021 | Published 10/06/2021

Question:

I have an old Trek brand child bike trailer, that also uses a ball on the end of the arm, attaching to an axle mounted cup. This cup looks very similar, but I wasnt sure if it was of a compatible size. Can you tell me what size diameter ball would fit in the cup? Could you also tell me what is the diameter of the mounting hole the hole which the axle goes through, and what is the thickness of the metal where the axle goes through?

asked by: Ben

Helpful Expert Reply:

The diameter of the holder for the coupling ball on the Replacement Bike Adapter ezHitch Cup # 50103033 is 1.14" which is just over 1-1/8". The diameter of that mounting hole it 7/16" and then the overall thickness is 1/4" but that little indention looks to be about 3/16". Attached is a photo to further demonstrate this.

expert reply by: Jon G